Is that actually Dee Dee? The blonde looks very different.
I am both shocked and puzzled at the amount of fear coming off of Blossom and Buttercup: aren't these two of the three girls who proved themselves to be extremely resilient by being bashed, smashed, and tossed about during their entire stay in Townsville? So why the fear over a sword and some tentacles? Come to think of it, all three girls seem to be severely downpowered from the feats they managed in the original material. Did they lose some of their power when they gained noses, necks, fingers, and toes? I'm not buying it; it must be simply for the sake of the Almighty Plot.
I've not got the time at the moment to check to see whether Jack has had the opportunity or reason to explain how his sword works in the presence of either the Girls or Sam -- and how would that come up without someone evil trying to use it anyway? So far Sam has used it to slice apart inanimate objects, but hasn't used it to cut anyone, right? I am therefore going to assume no intel on the sword, especially after BR's comment regarding the revelation of its nature -- it woudn't be shocking otherwise.
As to acting of its own accord and a moral loophole, I have been hanging onto this idea of the sword's backlash since, I think, the first page of this thread: knowing how little Sam cares about herself and her general attitude of the past couple pages (slightly nihilistic to active pursuit of causing anguish in others), I do not doubt that the sword will consider her to be 'evil.' Blossom, meanwhile, is trying to protect those around her from a perceived threat (plus she's made of Sugar, Spice, Everything Nice, and Chemical X), so the sword should see her as 'good.' The machine part of Sam may confuse the issue to the point where the sword may not perceive her as 'alive,' even if it does see her as 'evil.' We've seen Jack carve up plenty of robots and cyborgs with the blade, so it only seems natural for me, at least, to assume that the sword will work on Sam.
So what if, in backlashing off of Blossom, it severely injures or kills Sam with the force and killing intent she intended to use on Blossom? The further moral issue comes in the form that when they can avoid it, heroes, do not kill the villains, instead allowing for the capture in the name of justice. If Sam got killed because of Blossom, I suspect this would have an impact on the latter, even though they were enemies. When, after all, have the Girls even intended on killing anyway?
All of this being said, with the Girls I find it unlikely that a sword will be the deciding factor as to who wins and who sets the bomb off. More likely it would be the abilities of those currently in the confrontation (I do not foresee any interference from the outside as possible). All the same, since she is studying under Jack, it would be nice to see his sword in Buttercup's hands. And then the discipline Jack has been trying to instil within her will be truly tested.